Rachel Unger and Dr. Randy Killorn. Iowa State University, Iowa State University, Dept. of Agronomy, Ames, IA 50011
Char made from corn stover added to soils has the potential to reduce the need for nitrogen fertilizer, as well as enhance certain soil properties. An incubation study was conducted to find how char interacts with a nitrogen fertilizer, as well as how it reacts in different soils. The study also helped with the understanding of how different amounts of oxygen present in the char will impact different soil properties. One hundred grams of two different Iowa soils were mixed with three different types of char. The three different types of char were pyrolized with three different amounts of oxygen in the reactor while the char was being formed, 0% (1), 10% (2) and 25% (3), respectively. Each of the chars was applied to the different soils at a rate of 17.9 Mg ha-1. Along with the char, urea was applied at rates of 0, 56, 112, and 224 kg N ha-1. Treatments were replicated three times. Soil tests for pH, nitrogen, phosphorus, potassium, ammonium, nitrate, organic matter and total carbon were performed immediately after application, and after one, two, four, six and eight weeks. The different chars significantly affected the total nitrogen, total carbon and pH. The total nitrogen in chars 2 and 3 decreased at the second week of sampling and increased thereafter. The total nitrogen in char 1 increased over time. The total carbon was lowest in char 3. During the duration of the study, the amount of total carbon decreased in chars 1 and 2, but remained steady in char 3. The pH of all three chars tended to decreased over time, but there was a slight increase in pH at the final sampling time. The conditions during pyrolysis, with respect to oxygen, influence how the char reacts with the soil.